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Meet the professor session: Osteoporosis:
Better Reporting of Fracture Risk
Jill Wong, MD, Andrew Thompson, MD
The goal of this session was to outline the current
state of bone density reporting, the scientific basis
for current reports and the development of new tools
to improve fracture risk reporting.
What Do We Learn From Bone Mineral Density (BMD)
Testing?
BMD and fracture risk are inversely related. Hip fractures
are the most clinically relevant outcome in terms of
morbidity and mortality. Hip dexascan (DXA) best predicts
hip fracture risk, with each standard deviation decrease
in femoral neck bone density increasing the age adjusted
risk of hip fracture 2.6 times. (1)
What Other Risk Factors Are Important in Hip Fracture
Prediction?
In a 1995 study, published in the New England Journal
of Medicine, Cummings et al. identified risk factors
for hip fracture in 9,516 white women over 65. (2) The
13 independent risk factors included:
• Age
• Maternal history of hip fracture
• Height at age 25
• Self-rated health
• Current use of benzodiazepines or
anticonvulsants
• Hyperthyroidism
• Current caffeine intake
• On feet < four hours per day
• Inability to rise from a chair
• Poor vision
• Resting pulse > 80
• Any fracture since age 50
• Low bone density.
The two factors that were identified as being protective
were:
• 20% increase in weight since age 25
• Walking for exercise.
How Are BMD Results Currently Used To Make Treatment
Decisions?
Based on the current WHO definition of osteoporosis,
anyone with a T-score < -2.5 should be treated. The
National Osteoporosis Foundation published guidelines
for women that recommended treating any woman with a
T-score < -2.0; and any woman with a T-score <-1.5,
with at least one additional risk factor. (3) In short,
the decision to treat a patient at risk for hip fracture
is dependant on the threshold values used to identify
patients "at risk".
How Can Hip Risk Reporting Be Improved?
The techniques used to measure bone mineral density
are fraught with problems, including poor concordance
between sites and different technologies. The WHO criteria,
based on BMD, produce inconsistent diagnoses of osteoporosis.
They are better applied in epidemiologic studies than
in individual threshold decision-making. Using BMD as
the sole criteria to define osteoporosis is likely a
gross oversimplification. A more appropriate approach
is to view BMD as one important risk factor of many,
in determining future fracture risk. There are current
models being developed, based on multiple risk factors
(BMD, age), which will likely give a much better prediction
of future fracture risk. They are not yet available
for clinical application.
References:
| 1. |
Cummings SR, Black DM,
Nevitt MC, et al. Bone density at various sites
for prediction of hip fractures, Lancet 1993;341:72-75.
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| 2. |
Cummings SR, Nevitt MC,
Browner WS, et al. Risk factors for hip fractures
in white women. Osteoporosis Foundation: Physician's
Guide to Prevention and Treatment of Osteoporosis.
Belle Mead, NJ, Excerpta Medica Inc., 1998. |
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Last updated: September 03rd, 2007
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